// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_
#define NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <vector>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "net/base/net_export.h"
#include "net/base/upload_data_stream.h"

namespace net {

class DrainableIOBuffer;
class IOBuffer;
class UploadElementReader;

// A non-chunked UploadDataStream consisting of one or more UploadElements.
class NET_EXPORT ElementsUploadDataStream : public UploadDataStream {
public:
    ElementsUploadDataStream(
        std::vector<std::unique_ptr<UploadElementReader>> element_readers,
        int64_t identifier);

    ~ElementsUploadDataStream() override;

    // Creates an ElementsUploadDataStream with a single reader.  Returns a
    // std::unique_ptr<UploadDataStream> for ease of use.
    static std::unique_ptr<UploadDataStream> CreateWithReader(
        std::unique_ptr<UploadElementReader> reader,
        int64_t identifier);

private:
    // UploadDataStream implementation.
    bool IsInMemory() const override;
    const std::vector<std::unique_ptr<UploadElementReader>>* GetElementReaders()
        const override;
    int InitInternal() override;
    int ReadInternal(IOBuffer* buf, int buf_len) override;
    void ResetInternal() override;

    // Runs Init() for all element readers.
    // This method is used to implement InitInternal().
    int InitElements(size_t start_index);

    // Called when the |index| element finishes initialization. If it succeeded,
    // continues with the |index + 1| element. Calls OnInitCompleted on error or
    // when all elements have been initialized.
    void OnInitElementCompleted(size_t index, int result);

    // Reads data from the element readers.
    // This method is used to implement Read().
    int ReadElements(const scoped_refptr<DrainableIOBuffer>& buf);

    // Resumes pending read and calls OnReadCompleted with a result when
    // necessary.
    void OnReadElementCompleted(const scoped_refptr<DrainableIOBuffer>& buf,
        int result);

    // Processes result of UploadElementReader::Read(). If |result| indicates
    // success, updates |buf|'s offset. Otherwise, sets |read_failed_| to true.
    void ProcessReadResult(const scoped_refptr<DrainableIOBuffer>& buf,
        int result);

    std::vector<std::unique_ptr<UploadElementReader>> element_readers_;

    // Index of the current upload element (i.e. the element currently being
    // read). The index is used as a cursor to iterate over elements in
    // |upload_data_|.
    size_t element_index_;

    // Set to actual error if read fails, otherwise set to net::OK.
    int read_error_;

    base::WeakPtrFactory<ElementsUploadDataStream> weak_ptr_factory_;

    DISALLOW_COPY_AND_ASSIGN(ElementsUploadDataStream);
};

} // namespace net

#endif // NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_
